7- micronutrient requirements during pregnancy Flashcards
calcium
no additional Ca req during pregnancy ( no change in maternal one mass during pregnancy) - intestine increases absorption during this time ( increase in active vitamin D - BUT this is not what causes the increase in intestinal absorption)
around _____ g of Ca are transferred to the fetus throughout pregnancy ?
25-30 g - majority of transfer sin the last trimester ( makes sense bc max period of skeletal growth )
% increase in calcium absorption
10% - may be due to an increase in calcium hormones – not vitamin D increase
how did they find out about increase in calcium absorption
due to the fact that, if the women does not et enough calcium in the diet, she will not lose maternal bone reserves, she absorbed more calcium - more efficiently
where is calcium transfer coming from ?
not from mothers bones, don’t want to sacrifice her bone health– probably survival mechanism
blood concentration of 1,25 (OH)2D ?
increases
calcium RDA during pregnancy
does not increase and stays at 1,00 mg/d = 19-50, or 1,300mg/d if under 18
phosphorus?
no additional intake needed bc 10% increase in absorption
phosphorus EAR and RDA
580 mg/d and 700 mg/d for both men and women
phosphorus if under 18 yrs?
goes up from 700 to 1250 mg/d
serum Mg does _____ during pregnancy
down - thought to be bc of hemodilution ( bc of similarity with serum potassium )
magnesium during pregnancy
it increases ( EAR an additional 35mg/d), this is bc there is no data on an increase in intestinal absorption therefore, with the extra weight gain the body is assumed to need more magnesium
RDA for mg during pregnancy ( 14-18, 18-30, 30+)
14-18 = 400 mg/d 18-30= 350 mg/d 30+ = 360 mg/d
EAR of magnesium for pregnant women
additional 35 mg/d ( based on weight gain associated with pregnancy)
iron during pregnancy
increases in the second and third trimester but it decreases in the first trimester ( lower than non-pregnent women bc no menstraul losses -6.4 mg/d ), but absorbance also increases
total usage of iron during preg
1,070 mg ( 250 basal loses, 320 mg for fetal and placenta deposition and 500 mg for increase in hemoglobin mass)
trimester increases in iron
6.4 mg/d at 18% absorbance, 2nd trimester 18.8 at 25% absorption and 3rd trimester is 22.4 mg/d at 25%
severe anemia associated with?
perinatal material mortality
moderate anemia associated with
twice the risk of maternal death - heart failure, hemorrhage and infection
large epidemiological studies show what is associated with anemia
premature delivery, LBW and increase in perinatal infant mortality
high HB concentration at eh time of delivery is associated with
adverse pregnancy outcomes ( U -shaped curve with low and high levels- need a balance) increased risk at greater than 130 g/L or less than 90 g/L
Hb range present women want to aim for
90 g/L and 130 g/L
why are there risks with high Hb levels?
may reflect a decrease in plasma levels–> maternal HPT and preeclampsia
what does iron supplement assume during pregnancy
that there were inadequate stores pre -pregnency –> if they were normal stores, supplement may not be nessasay
iron RDA for pregnancy
27 mg/d for all age groups
what is RDA based on
3rd trimester, build iron stores during the first trimester ( bc assuming inadequate stores) and using an upper limit of 25% absorbance, CV of 10% for RDA= 120% of EAR
AI for potassium
no change –> 3.4 males and 2.6 females this was recently decreased from 4.7 g/d bc of lack of evidence) - was higher before ( to do with more K increases Na excretion)
sodium in pregnancy
should women with preeclampsia or hypertension decrease salt intake?
extra 2.1 -2.3 g over the 9 months –> Na in order to maintain plasma volume,
0.07g/d additional per day –> o bc it is so minimal the AI does not change –> still 1.5 g/d
should women with preeclampsia decrease salt intake? no there is no effects- there are other factors involved- mostly overweight stays- so they should not
Thiamine RDA
requirement increase by 30% –> 1.4 mg/d from 1.1 mg/d ( normal women) growth (20%) and (10%) for increase in energy utilization- thiamin functions as a coenzyme in the metabolism of CHO and BCAA(RBC transkelotase, thiamin pyrophosphate -TPP)
Riboflavin RDA
up from 1.1 mg/d to 1.4 mg/d (same as thiamine) –> additional 0.3 mg/d is to do with increased growth in maternal and fetal compartment san dnincreas tin energy ( less urinary excretion of riboflavin and frequent appearance of clinical signs in women with low intake)
Niacin RDA
increase from 14mg/d NE to 18mg/d, due to estimate that increased energy and growth would need more niacin however no direct intake
vitamin B6 (pyridoxine) RDA
increases to 1.9 mg/d, bc significant fetus uptake of B6 (especially in the second half of gestation) but we do not store B6 efficiently so unlikely that excess in early gestation would do anything, need an extra 0.6 mg/d to meet needs
fetus and placenta accumulate how much B6 during the entire pregnancy
25 mg( about 0.1 mg/d)
in order to maintain pyridoxal phosphate ( which is the common marker ) how many mg B6 would need to be supplemented? why is this not the current RDA?
1mg/d in first semester and 4-0 mg/d the 2nd and 3rd.
however the RDA is 1.9mg/d, this is bc even though this marker decreases there is no efficiency that there is an issue with this- this may be a normal physiological change
( more than just hemodilution)
- however, 25mg over the course of the pregnency is needed to accumulate in the placenta and the fetus which is about 0.1 mg/d–> we over shoot this and make the RDA 1.9 g/d ( bc of metabolic needs of mother, and additional average pregnancy need and -75% bioavailability)
why does folate req increase so dramatically ?
increase in single carbon transfer reactions –> cell division and nucleotide synthesis –> uterine enlargement, placenta dev, expansion of maternal erythrocyte number and fetal growth
what happens with inadequate folate status?
megaloblastic anemia, marrow changes low folate concentration ad maternal serum and RBC
what is the primary indicator of adequacy for folate
erythrocyte folate maintenance ( reflects storage in tissues)
folate EAR and RDA during pregnancy
EAR= 520 ug/d ( derived from EAR for non pregnancy women ( 320 ug/d) + 200 ug/d--> found that low intake + 100 g supplement was inaqequate) RDA = 600 ug/d and women that are capable of becoming pregnant need to be taking 400 ug/d from fortified foods, sups or both + CONSUMING FOOD FOLATE from a varied diet to prevent NTD
all women should be taking?
400 ug/d supplement or fortified food
- this is unto of food folate ( basically saying food folate doesn’t count )
why does B12 absorption increase during pregnency
increased number of intrinsic factor B12 receptor
B12 (cobalamin) EAR and RDA
EAR increase by 0.2 ug/d, RDA 2.6 ug/d
are maternal liver stores of B12 important for the fetus
not really, only the newly absorbed B12 gets transported across the placenta ( the current B12 intake during pregnancy and the absorption are more important than pre-stores)
biotin during pregnancy
no additional requirement
- recent studies are conflicting- showing either a high or low plasma concentration
- increase in biotin metabolite in half population and then a decrease in urinary excretion in half population
- unknot if normal physiological change or if indicative of low intake
factors affecting biotin requirement
- consuming raw egg whites increase need ( avidin)
- biotinidase def decreased the function of the enzyme- increases need
- anticonvulsants induce biotin catabolism, increasing need
choline AI? increase?
AI= 450 mg/day ( increase of 25mg/day)
- requirement increases bc fetus needs a lot and could deplete mothers status
choline def in preg leads to
increase in homocysteine -> birth defects ( and 90% of Americans are NOT ingesting enough choline- may be done through eggs)
pantothenic acid and preg
no info that usual intake is inadequate, AI = 6mg/d
vit C EAR? increase? RDA
maternal vit C concentration goes down - hemodilution and active transfer to the fetus so additional vit C is needed
EAR= increase 10mg/d RDA= 85 mg/d
subpopulations may need more vit C such as
smokers, heavy alcohol use, regular aspirin use
greater than20 cigs a day need twice as much vitamin C–> 35 more mg
vitamin A requirement increases?
about 50 ug/d during last trimester ( most of accumulation happens in the last 90 days)
vitamin A EAR
50 ug/d + EAR for non prep women (530ug/d)
Vitamin A RDA
770 ug/d RAE
UL of vit A is based on what?
teratogenicity, whereas in non pregnancy it is based on liver abnormalitites
Vitamin D
small quantities transferred to the fetus –> no additional need during pregnancy
vitamin E
no additional intake needed–> but there have been causes of vitamin E deficiency in premature newborns, however o data that supplement vit E would have prevented this
Vitamin K
no additional intake needed during pregnancy –> stays at 90 ug/d (120ug/d men )
folate to the cord blood is
active transport
folate biomarker (most accurate)
RBC folate bc reflects tissue stores
synthetic form of 100 ug folate ( equal to 200 ug of dietary folate form ) caused?
found to be insufficient so add this base to the non pregnent EAR ( 320 ug/d) = 520 ug/d
to ensure all women get covered, assume that all women going into pregnancy are low folate
synthetic form of B12
is bioavailable boy itself, doesn’t need intrinsic factor
serum (B12) levels _____ in first semester
decrease
- mother taking up more
if mother is on a B12 deficient diet can the fetus use maternal liver stores of B12 ?
can last up to 2-3 years before signs of anemia, however for the fetus- these stores are less bioavailable ( issue with fetal uptake) fetus only wants the newly absorbed B12
Choline
brain development - animal studies with increased spatial memory
- -> offspring had faster processing ( with higher supplementation of choline)
- -> may be higher supplest need - choline acts as a NT
- involved in the methionine metabolism
choline in methane metabolism
choline –> cofactor betaine– betaine is cofactor for homocysteine to methionine
( insufficient phosphatidylcholine leads to fatty liver)
- dietary studies have linked low choline to NTD bc of the homocysteine to methionine
sources of choline
fish, eggs, animal protein, cauliflower, Brussel spouts
hypo-methylation linked to
deficient B12, folate and choline
leads to increased cortisol at placenta, epigenetic
high folate acid supplementation
increased risk of colon cancer
- hyper- methylation
methylate checkpoints
2 main factors that amount for additional protein req
new tissue growth
maintain of
teratogenic effects (malformations) with protein def? with iodine?
microcephaly , cretinism
folate
population studies and confirm that a combination of ≈681 nmol (300 μg) synthetic folic acid/d from supplements, fortified food, or both plus ≈227 nmol (≈100 μg) dietary folate/d is sufficient to maintain normal folate status during pregnancy. Expressed as a DFE, the consistent finding across the numerous population studies and the controlled metabolic study is that 1362 nmol (600 μg) DFE/d is adequate to maintain normal folate status.
